Criteria for the credit deduction from the free 500 hours

I am using a MySQL service from Railway in a flask application deployed on the web using Render. I was wondering if I would be charged even when no one is using my application.

Also, if I am continuously charged, is there a way to stop the service temporarily when my application hasn't been accessed for a long time and then reboot it again when someone tries to access it?
this is currently not supported by railway, you'd need to delete your service if you didn't want to be charged for it.